<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>水平线</title>
</head>
<body>
<p>hr 标签定义水平线：</p>
<hr/>
<p>这是段落。</p>
<hr/>
<p>这是段落。</p>
<hr/>
<p>这是段落。</p>
</body>
</html>